That's why I asked what he was using for bedding.I use papertowel and don't spray directly on the papertowel i moist a towel and put it on top, and mist lightly.. I have my other in a tub and generally don't have to worry about the humidity at all.
I believe if you have to constantly mist all day everyday, just to barely keep the humidity up, than it's time to figure something out because in my opinion, I'm far from a professional but THAT would cause scale rot.. I have never had the issue (knock on wood).